Hunters beware: California's public lands are threatened by more and more illegal marijuana growing operations, with armed crews toting powerful weaponry.

That message Sunday during the 24th International Sportsmen's Exposition at Cal Expo came from a law enforcement panel that included state game wardens, a wildlife advocate and a Bureau of Narcotic Enforcement task force commander.

The Mexican drug networks have turned largely to California and its Mediterranean climate for their operations that now supply much of the country with the weed, the panelists said.

As a result, those operations are an increasing threat to outdoor enthusiasts, sportsmen and women and any other passers-by who might not recognize the danger signals of trash, irrigation equipment and stream diversions, they said.

In addition, the illicit growers use fertilizers for plant growth and chemicals to kill any animals, large or small, that typically inhabit the area. Runoff, in turn, pollutes nearby streams and can affect sources of downstream drinking water.

Nancy Foley, chief of the Law Enforcement Division for the state Department of Fish and Game, called illegal marijuana cultivation "the No. 1 destroyer of habitat in the United States."

State Fish and Game Warden Lt. John Nores Jr., co- author of a new book, "War in the Woods – Combating the Marijuana Cartels on America's Public Lands," agreed with that sentiment and said the problems go well beyond public safety.

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